Section 163.555 - Criminal nonsupport(1) A person commits the crime of criminal nonsupport if, being the parent, lawful guardian or other person lawfully charged with the support of a child under 18 years of age, born in or out of wedlock, the person knowingly fails to provide support for such child.(2) It is no defense to a prosecution under this section that either parent has contracted a subsequent marriage, that issue has been born of a subsequent marriage, that the defendant is the parent of issue born of a prior marriage or that the child is being supported by another person or agency.(3) It is an affirmative defense to a prosecution under this section that the defendant has a lawful excuse for failing to provide child support.(4) If the defendant intends to rely on the affirmative defense created in subsection (3) of this section, the defendant must give the district attorney written notice of the intent to do so at least 30 days prior to trial. The notice must describe the nature of the lawful excuse upon which the defendant proposes to rely. If the defendant fails to file notice as required by this subsection, the defendant may not introduce evidence of a lawful excuse unless the court finds there was just cause for the defendant's failure to file the notice within the required time.(5) Criminal nonsupport is a Class C felony. 1971 c.743 §175; 1993 c.33 §308; 1999 c.954 §3; 2005 c. 502, § 1